This disclosure relates to a light emitting diode (LED) with a contact that induces an electromagnetic field within in the LED for shaping the light emitted by the LED.
LEDs convert electrical energy into optical energy. In semiconductor LEDs, light is usually generated through recombination of electrons, originating from an n-type doped semiconductor layer, and holes originating from a p-type doped semiconductor layer. As used herein, the term “light” includes not just visible light, but also electromagnetic radiation having a wavelength outside that of the visible range, including infrared and ultraviolet radiation.
Prior bottom-emitting micro-LEDs (“μLEDs”) include a semiconductor with a quantum well, a uniform p-contact at the top of the μLED structure, and an n-contact. When a current flows between the p-contact and the n-contact, light is emitted from the quantum well. The inner walls of the μLED reflect light, and if the LED has a semi-parabolic shape, the walls will direct the reflected light out the bottom of the LED. The shape of such μLEDs could improve the extraction efficiency of the μLED and the directionality of the emitted light beam over prior LEDs, such as traditional cuboid shaped LEDs. However, a cavity effect between the p-contact and the quantum well could create a sub-optimal radiation pattern in the emitted light. For example, if the cavity effect guides light that emitted from the quantum well straight towards the bottom of the LED, rather than towards the reflecting walls the μLED structure, the light that is emitted will not be collimated and instead will diverge after exiting the μLED.